feat: implement OpsBridge CLI (BRIDGE-WP-0001)

Full TDD implementation of the `bridge` CLI tool covering all phases
from BRIDGE-WP-0001: project scaffolding, config loading, state
management, audit logging, health checks, tunnel lifecycle manager, and
all CLI commands (up/down/restart/status/logs). 77 tests, all green.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_state.py

@@ -0,0 +1,69 @@
+"""Tests for state management."""
+import os
+import signal
+
+import pytest
+
+from bridge.models import BridgeState
+from bridge.state import StateManager
+
+
+@pytest.fixture
+def state_dir(tmp_path):
+    return tmp_path / "bridge"
+
+
+@pytest.fixture
+def mgr(state_dir):
+    return StateManager(state_dir=state_dir)
+
+
+class TestStateManager:
+    def test_read_state_no_file_returns_stopped(self, mgr):
+        assert mgr.read_state("my-tunnel") == BridgeState.STOPPED
+
+    def test_write_and_read_state(self, mgr):
+        mgr.write_state("my-tunnel", BridgeState.CONNECTED)
+        assert mgr.read_state("my-tunnel") == BridgeState.CONNECTED
+
+    def test_state_roundtrip_all_values(self, mgr):
+        for state in BridgeState:
+            mgr.write_state("t", state)
+            assert mgr.read_state("t") == state
+
+    def test_write_pid(self, mgr):
+        # Write a live PID (our own process) so read_pid can confirm it's alive
+        pid = os.getpid()
+        mgr.write_pid("my-tunnel", pid)
+        assert mgr.read_pid("my-tunnel") == pid
+
+    def test_read_pid_no_file_returns_none(self, mgr):
+        assert mgr.read_pid("nonexistent") is None
+
+    def test_stale_pid_returns_none(self, mgr):
+        # PID 999999 almost certainly does not exist
+        mgr.write_pid("my-tunnel", 999999)
+        assert mgr.read_pid("my-tunnel") is None
+
+    def test_current_pid_is_alive(self, mgr):
+        mgr.write_pid("my-tunnel", os.getpid())
+        assert mgr.read_pid("my-tunnel") == os.getpid()
+
+    def test_clear_pid(self, mgr):
+        mgr.write_pid("my-tunnel", os.getpid())
+        mgr.clear_pid("my-tunnel")
+        assert mgr.read_pid("my-tunnel") is None
+
+    def test_state_dir_created_on_write(self, state_dir):
+        assert not state_dir.exists()
+        mgr = StateManager(state_dir=state_dir)
+        mgr.write_state("t", BridgeState.STOPPED)
+        assert state_dir.exists()
+
+    def test_is_running_false_when_stopped(self, mgr):
+        assert not mgr.is_running("my-tunnel")
+
+    def test_is_running_true_when_pid_alive(self, mgr):
+        mgr.write_pid("my-tunnel", os.getpid())
+        mgr.write_state("my-tunnel", BridgeState.CONNECTED)
+        assert mgr.is_running("my-tunnel")